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Contest: Task: Related: TaskA TaskC

Score : $200$ points

Problem Statement

Given a positive integer $N$, find the maximum integer $k$ such that $2^k \le N$.

Constraints

  • $N$ is an integer satisfying $1 \le N \le 10^{18}$.

Input

Input is given from Standard Input in the following format:

$N$

Output

Print the answer as an integer.

Sample Input 1

6

Sample Output 1

2
  • $k=2$ satisfies $2^2=4 \le 6$.
  • For every integer $k$ such that $k \ge 3$, $2^k > 6$ holds.

Therefore, the answer is $k=2$.

Sample Input 2

1

Sample Output 2

0

Note that $2^0=1$.

Sample Input 3

1000000000000000000

Sample Output 3

59

The input value may not fit into a $32$-bit integer.